E2: Neuromuscular process of muscular contractions Flashcards
when can a skeletal muscle contract?
when stimulated by electrical impulses from a CNS
what are motor neurones?
-specialised cells that transmit nerve impulses from the CNS in the brain and spinal cord to the muscle fibres
-the nerve that connects to the muscle fibre
Whats the CNS made up of?
-cell body
-axons
-motor end plate
where is the cell body located?
in the spinal cord
where is the cell body located?
in the spinal cord
what do axons do?
branch off the cell body and send impulses to the motor end plates
whats a motor end plate?
where the action potential from an action travels to stimulate a muscle
what makes up a motor unit?
motor neurone + muscle fibres
-a motor neurone provides muscle fibres with a signal
whats the synapse inbetween the motor neurone and the muscle fibre called?
Neuromuscular junction
what happens to a signal when it comes to the end plate of a motor neurone?
the impulse crosses the junction to activate the muscle fibre
what is a synapse?
a connection point between 2 neurones
What is the nuromuscular junction?
-a synapse between motor neurone and muscle fibre
-converts electrical impulses into electrical activity in the muscle fibre.
What is a neurotransmitter?
a chemical messanger in the body, their job is to transmit signals from nerve cells to target cells(muscle fibre)
what is a acetylcholine?
a chemical transmitter/neurotransmitter that is responsible for muscular contraction
what is action potential?
the electrical impulse that makes the muscle contract
what is the flow diagram of the neuromuscular process of muscular contractions?
nervous impulse->
arrives at the neuromuscular junction->
acetylcholine is released->
action potential allows for muscle fibre to contract->
Muscle fibre contracts.
what happens to the signal when it is received by the muscle fibre?
the signal is spread throughout the muscle fibre/myofibril in order for the whole muscle fibre to contract.
when can action potential be made?
when there is enough acetylcholine
true or false: motor neurones cause contractions of a number of different muscle fibres
true
what is the name of the tubes that the signal travels down to reach the filaments/myofibril?
T-tubules
how do thin filaments in myofibril contract?
slide across eachother
whats a sarcomere?
the functional part of the myofibril which consists of I,A and H bands
what is actin?
thin protein filament
what is myosin?
thick protein filament
what do calcium ions do in the process?
work within the neurotransmitter to send signals and facilitate the muscular contraction
whats troponin?
a group of proteins found in skeletal muscle fibres to regulate muscle contractions
what is tropomyosin?
contractile proteins which work with actin and myosin
what is the Z line?
the line at the edge of each sarcomere
whats the H zone?
zone which contains the myosin filament
whats the A band?
zone that contains the length of the sarcomere with the myosin filaments and does not change size during contractions.
It can can contain just the myosin filaments(resting) or contain both actin and myosin(contracting)
whats the I band?
the zone around the Z lines and includes part of the 2 sarcomeres. It only contains actin filaments and gets smaller when muscles contract
how does acetylcholine turn into action potential?
the acetylcholine receptors detect whether or not there is enough acetylcholine, if their is action potential is released
whats a cross bridge?
when actin and myosin attatch
whats ATP?
energy used to pull and contract the actin and myosin
whats it called when myosin and actin attatch and move?
power stroke
when does a muscle contraction engage?
when the action potential arrives at the neuromuscular junction?
what does the action potential arriving at the neuromuscular junction trigger?
calcium ions to be released from the sarcoplasmic reticulum and starts the process
What does the calcium ions attatch to?
the troponin
when calcium attatches to troponin, what happens?
the troponin moves/changes the shape of the tropomyosin, therefore exposing the binding sites.
what can happen now that the binding sites have been exposed?
the myosin can then bind to the actin and causes a cross bridge to be formed.Once the cross bridge has been formed the muscle can now contract.
why will the muscle shorten during contraction?
because the myosin is pulling the actin in.
the process of myosin pulling actin in can continue as long as what?
there is sufficient ATP
when will the mysosin detatch?
once the process has stopped or theres isnt enough calcium or ATP
what happens to the muscle once the contraction has stopped?
the muscle will relax and become longer
what are the 3 different types of muscle contractions?
-isometric
-concentric
-eccentric
what is a concentric contraction?
-contraction when the musle shortens and develops tension.
-A movement must occur against gravity
what happens to the origin and insertion during concentric contractions?
the origin and insertion move closer together.
what is a eccentric contraction?
-contraction when the muscle lengthens to deelop tension
-movement must occur in a downwards phase to resist gravity
what happens to the origin and insertion during eccentric contractions?
the origin and insertion move further apart from each other
Whats a isometric contraction?
-“iso” means it does not change under tension-if the contraction creates tension but stays the same length then its isometric.
when does an isometric contraction occur?
when the body is being fixed in 1 position
